[백준] 8393번

import java.util.Scanner;
public class Main {
    public static void main(String[] args) {

        Scanner sc = new Scanner(System.in);

        int A = sc.nextInt();
        int sum = 0;

        for (int i = 1; i <= A; i++) {
            sum += i;
        }
        System.out.println(sum);
    }
}